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By Saurabh Datar |Posted 23-Feb-2014

The website, chordify.net, analyses your favourite song and instantly gives you its chords for free

Hear, hear! Professional and aspiring musicians, the next time you want to learn how to play a song, there’s a website which gives you its chords in an instant.

Founders of Chordify, Bas de Haas and Tijmen Ruizendaal

Chordify.net is a handy service that analyses a song and extracts its chords. You can post a YouTube or a Soundcloud link, or you can upload a music file as well. Feed in your song, and start playing to the chords as they show up on screen.

Chordify works on a music information retrieval algorithm developed by Bas de Haas, a researcher at Utrecht University in Netherlands. The programme was his PhD thesis, on which he had worked for four years. De Haas is also a musician and has a band with fellow Dutchman Tijmen Ruizendaal, who is also the co-founder of Chordify. “We were jamming one day when Bas suddenly came up with an idea for a service to recognise chords in a song. We went ahead and actually did it,” says Ruizendaal, who is the front-end developer for the website.

How it worksChordify uses Fourier transformation of sound files to analyse frequencies. Fourier transformations are used to transform signals between time and frequency domains, usually seen in graphic representations as continuous spikes and troughs.

“The algorithm breaks down a song into pieces of 10 milliseconds each and searches for higher frequencies, which may represent chords, say a C or a G chord. It calculates the chance that these frequencies may be chords, and rescans it to narrow down to the final chord,” explains the 29-year-old Ruizendaal.

However, all you see is a neat chart of chords that you can play along with the song. You can even put it on loops to practise and master the piece.

However, the software is not 100 per cent accurate. “If it’s a simple pop song, the accuracy is about 90 per cent. As the chords become more complicated, the detection goes wrong,” he confesses. Neither does it recognise chords beyond the simpler majors and minors — the sevenths, minor sevenths, diminished, suspended etc are not included. So you can’t expect a jazz standard to unravel in front of you. “We’re working on adding the sevenths soon,” he says. De Haas and a fellow researcher contribute to the website’s algorithm improvement.

But, do musicians frown upon it? “Not all. It’s useful to know the basic chords. I have a friend who is a guitarist, but he still uses Chordify to practise,” adds Ruizendaal, who plays drums and the guitar. Considering it instantly determines the chords to a music piece, it’s quite useful, especially for beginners and casual players.

The group (six people including programmers and designers) also launched their paid ‘Premium’ features, which allow you to transpose songs to different scales, change speed, among others. The site, with more than 2.5 million users, will soon have apps for Android and iOS. Another feature to be introduced is editing of chords by users. “We keep getting requests for editing of chords. Anyone who finds a mistake in a song can edit it to the correct chord.”

Hitting the high notesOver 2.5 million Number of users

Over 1 millionSongs whose chords are available on the website

How to use Chordify>> Log on to www.chordify.net>> Copy a YouTube URL or a Soundcloud URL of a music piece. You can also upload a file of your own>> Press the ‘Chordify’ button and start playing!